>do you think that gcc is MALLOCing (hehe) all space with one call instead
>fallow the program order (malloc 1 space at time) ?

you've misunderstood. we'd already discovered that all the extra time compared
to Linux was caused by having changed the program to do single writes via print
instead of buffered writes via printf (by the way, if you send
the output to /dev/null, the effect is much less, but even so).

geoff then showed how to make the program run even faster on either system,
assuming that was your main aim.  he also showed that there were some bugs in
the original code (eg not returning a value from bstini,
which only happens to work because both compilers happen to leave the result
of malloc in the right place to be taken as a returned value by the caller of 
bstini).